On Thu, Jun 06, 2013 at 12:28:16AM +0800, 李春奇 <Arthur Chunqi Li> wrote:
> On Thu, Jun 6, 2013 at 12:13 AM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
> > This time the email is perfect :)
> >
> > On Thu, Jun 06, 2013 at 12:02:52AM +0800, Arthur Chunqi Li wrote:
> >> Add multibyte NOP test case to kvm-unit-tests. This version adds test cases into x86/realmode.c. This can test one of bugs when booting RHEL5.9 64-bit.
> >>
> >> Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx>
> >> ---
> >> x86/realmode.c | 24 ++++++++++++++++++++++++
> >> 1 file changed, 24 insertions(+)
> >>
> >> diff --git a/x86/realmode.c b/x86/realmode.c
> >> index 981be08..e103ca6 100644
> >> --- a/x86/realmode.c
> >> +++ b/x86/realmode.c
> >> @@ -1504,6 +1504,29 @@ static void test_fninit(void)
> >> report("fninit", 0, fsw == 0 && (fcw & 0x103f) == 0x003f);
> >> }
> >>
> >> +static void test_nopl(void)
> >> +{
> >> + MK_INSN(nopl1, ".byte 0x90\n\r"); // 1 byte nop
> >> + MK_INSN(nopl2, ".byte 0x66, 0x90\n\r"); // 2 bytes nop
> >> + MK_INSN(nopl3, ".byte 0x0f, 0x1f, 0x00\n\r"); // 3 bytes nop
> >> + MK_INSN(nopl4, ".byte 0x0f, 0x1f, 0x40, 0x00\n\r"); // 4 bytes nop
> > But all nops below that are not supported in 16 bit mode. You can
> > disassemble realmode.elf in 16bit node (objdump -z -d -mi8086
> > x86/realmode.elf) and check yourself. Lets not complicate things for now
> > and test only those that are easy to test.
> Yes. But what if a 7-bytes nop runs in 16bit mode? Just the same as
> https://bugzilla.redhat.com/show_bug.cgi?id=967652
>
It cannot. In 16 bit mode it is decoded as two instructions:
0f 1f 80 00 00 nopw 0x0(%bx,%si)
00 00 add %al,(%bx,%si)
> DR6=00000000ffff0ff0 DR7=0000000000000400
> EFER=0000000000000500
> Code=00 00 e9 50 ff ff ff 00 00 00 00 85 d2 74 20 45 31 c0 31 c9 <0f>
> 1f 80 00 00 00 00 0f b6 04 31 41 83 c0 01 88 04 39 48 83 c1 01 41 39
> d0 75 ec 48 89 f8
>
> The error code is "0f 1f 80 00 00 00 00", which is a 7-bytes nop. Will
> the emulator runs well in that case when booting RHEL5.9 64-bit?
>
> Arthur
>
>
> >
> >> + MK_INSN(nopl5, ".byte 0x0f, 0x1f, 0x44, 0x00, 0x00\n\r"); // 5 bytes nop
> >> + MK_INSN(nopl6, ".byte 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00\n\r"); // 6 bytes nop
> >> + MK_INSN(nopl7, ".byte 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00\n\r"); // 7 bytes nop
> >> + MK_INSN(nopl8, ".byte 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00\n\r"); // 8 bytes nop
> >> + MK_INSN(nopl9, ".byte 0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00\n\r"); // 9 bytes nop
> >> + exec_in_big_real_mode(&insn_nopl1);
> >> + exec_in_big_real_mode(&insn_nopl2);
> >> + exec_in_big_real_mode(&insn_nopl3);
> >> + exec_in_big_real_mode(&insn_nopl4);
> >> + exec_in_big_real_mode(&insn_nopl5);
> >> + exec_in_big_real_mode(&insn_nopl6);
> >> + exec_in_big_real_mode(&insn_nopl7);
> >> + exec_in_big_real_mode(&insn_nopl8);
> >> + exec_in_big_real_mode(&insn_nopl9);
> >> + report("nopl", 0, 1);
> >> +}
> >> +
> >> void realmode_start(void)
> >> {
> >> test_null();
> >> @@ -1548,6 +1571,7 @@ void realmode_start(void)
> >> test_xlat();
> >> test_salc();
> >> test_fninit();
> >> + test_nopl();
> >>
> >> exit(0);
> >> }
> >> --
> >> 1.7.9.5
> >
> > --
> > Gleb.
--
Gleb.
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